The invention relates to high pressure high temperature (HPHT) press apparatuses. For example, such presses are useful in the superhard materials production industry. Some examples of superhard materials high pressure high temperature presses produce and sinter include cemented ceramics, diamond, polycrystalline diamond, and cubic boron nitride. HPHT press apparatuses require significant structural mass to withstand the ultra high pressures essential to synthetically form superhard materials. Uneven strain distribution across the threaded interface of press components, such as a hydraulic cartridge and unitary frame, cause increased cyclical fatigue promoting early failure in the cartridges and/or frame. Various press designs are known in the art of superhard materials production and have employed assorted concepts to contain the immense reaction forces that are required to process superhard materials. For example, U.S. Pat. Nos. 2,918,699 and 3,913,280 disclose a tie-bar frame press design. The tie bar press relies on press mass largely to prevent press rupture during press cycle in which bending moments of the tie bars become great. Other versions employ a polyhedral frame of six crossheads to prevent press rupture during the cycle such as disclosed in U.S. Pat. No. 2,968,837.
The presses are often classified by the tonnage of pressure they are capable of exerting on a reaction cell, the container which is inserted into the press reaction chamber that houses the sintering raw material for transformation under high pressures and temperatures into superhard materials. For example, a 3000-ton multi-axis press typically is capable of producing approximately 700,000 p.s.i. on each face of a cubic reaction cell. During the press cycle, the reaction cell is usually subject to ultra high compressive forces and temperatures; the pressure inside the cell must reach 35 kilobars or more to produce superhard materials such as polycrystalline diamond. Simultaneously, an electrical current is passed through the cell's resistance heating mechanism raising the temperature inside the cell to above 1000° C. After the reaction cell is subject to high pressures and temperatures for a set period of time, it is quickly cooled. Pressure is then released on each side of the cell and the cell is removed from the internal reaction chamber.
The amount of compressive forces a high pressure high temperature press can exert on a given reaction cell and consequently the maximum reaction cell size and payload, are limited by the reaction forces the press can endure without catastrophic rupture. Most often, the size and mass of the press determines its threshold capabilities for tonnage before catastrophic rupture occurs. For example, the weight of a tie-bar press with a tonnage rating of 3000 may exceed 60 tons. The weight of a 4000-ton tie bar press may exceed 100 tons. Moreover, large tonnage press types as described above are often expensive to construct and its efficiency is typically proportional to the duration of its cycle and volume of its payload. Therefore, in general, the smaller the press mass and the shorter the duration of the pressing cycle, and the larger the reaction cell is with concomitant enlarged payload volume, then the higher the economy and efficiency of the multi-axis press. Essentially, the greater reaction forces a press design can withstand at a given mass in conjunction with decreased energy consumption per cycle and increased reaction cell payload, then the manufacture of superhard materials becomes more viable.